1. Field of the Invention
The invention relates to hydraulic anti-vibratory support sleeves including two rigid tubular frames, one surrounding the other, preferably of revolution at least partially, coaxial and concentric at least under load, which frames are joined together by a elastomer body adhering thereto and shaped so as to form therewith at least two diametrically opposite sealed pockets communicating therebetween through a narrow channel, the assembly of said pockets and said channel being filled with a shock absorbing liquid.
Such sleeves are intended to be mounted between two rigid pieces fixable respectively to the two frames and adapted to undergo, with respect to each other, oscillation oriented in a diametrical direciton D with respect to the axis common to the two frames, the assembly being arranged so that, for some at least of these oscillations, the liquid is driven alternately from one of the pockets towards the other and conversely through the narrow channel, which creates in this liquid, for certain oscillation frequencies, a resonance phenomenon capable of damping the transmission of these oscillation from one of the frames to the other.
The sleeves of the kind in question are for example intended to be inserted between a vehicle chassis and the internal combustion engine or the front or rear undercarriage.
2. Description of the Prior Art
The invention relates more particulary, among the above support sleeves, to those in which the portion of the elastomer body which defines one at least of the pockets has in axial section the general shape of a radially outwardly open V, such as described in patent U.S. Pat. No 3,698,703: these sleeves lend themselves to relatively large resilient deformations representing relatively high mutual tilting of the axes of the two frames.
In presently known embodiments of these sleeves, the narrow channel which connects the two pockets together is generally formed by a channel in the form of an arc of a circle extending in the median transverse plane of the sleeve, along the internal frame or, more rarely, along the external frame.
These embodiments have the following drawback: the narrow channel is relatively far removed from the endmost axial faces of the sleeve, which raises problems for filling this sleeve with liquid and for providing sealing, such filling having to be carried out before the external frame is positioned about the elastomer body.
Furthermore, it is not possible to modify the dimensions of the narrow channel, and so the damping characteristics fo the sleeve, after manufacture thereof.
The aim of the invention is, especially, to overcome these drawbacks.